Some questions

[Martin Baeker <baeker@x4u2.desy.de>]

Hi,
my name is Martin B"aker (like "Baker", but with this funny German "Umlaut").
I'm another dinosaur enthusiast from Germany (dinosaur developing 
country), reading this mailing list for a few weeks now, so I thought 
it's time to say hello and get rid of some questions - if the mail server 
can digest them...

I am somewhat confused about the widespread agreement that sauropodes 
definitely lived on land. I agree that they look like being built for it, 
but I have read in several different books about sauropod footprints 
showing that they were swimming (at least sometimes), because only tracks 
of the forelimbs are left. If they did not like water and swampy ground 
very much (as suggested in the "heresies"), were did these come from?
Now I just read that one hypothesis is that this is due to the larger 
pressure exerted by the forelimbs, but I also read (don't know where or 
when) that sometimes a hindlimb print can also be seen and then the 
track changes direction. So this would definitely mean they were 
swimming. Or were they hydrogen-filled after all and these were their 
landing tracks? 

I have also recently read the dinosaur book by the Czerkas', which IMHO 
contains very interesting stuff on protomammals etc., but was really 
somewhat strange in the dinosaur part. Is really *every* interesting 
structure in dinosaurs related to thermoregulation?
To be more specific: Is it true what they write about the hadrosaurs: 
Those with large, high crests lived in climatically different regions from 
those with small ones? And could ceratopian (note the ommission of the 
"s"!) horns really be used for thermoregulation? Wouldn't that mean that 
they contain lots of blood vessels close to the surface? If I were a 
Triceratops, I would really hate to fight anyone with such a sensible 
structure...

Commenting on recent discussions about dinosaut sizes: I think terms like 
small, medium, large should only be used with respect to some identifying 
noun: A 20cm spider is surely a large spider, but at most a medium-sized 
animal. The same should hold for dinosaurs: A small sauropod may 
nevertheless be considered a large dinosaur. So, if you want to use size 
as a criterion to identify something, take into account what you already 
know about it: If you only know it's a dinosaur and it's pretty large 
(for a dinosaur), it probably is a sauropod - even if it's small for this 
group. Whew - this sounds pretty complicated, although I thought it's 
quite simple - did anybody guess by now that I am doing theoretical physics?

By the way, the idea of a supernova having caused mass extinctions is not 
new: I have read a paper by J. Ellis and D. Schramm from 1993 where they 
calculate some of the consequences. Their conclusion is that a supernova 
in about 30ly distance from earth would only have negligible effect on 
the earth's temperature and the radiation would increase by a factor of 
ten to 100 compared to the normal value. However, it might destroy the 
ozone layer of the earth by producing large quantities of NO (nitrogen 
oxid), which is a catalyst for destroying ozone. I leave it to you to 
decide whether this would be able to cause an extinction like that of the 
dinosaurs and all the other species that were killed at that time. They do 
not say anything on neutrinos - probably because they 
believe their effect to be extremely small, as they have a nearly 
vanishing reaction rate with matter, as has already been stated before.

Thanks for any answers or comments,
Martin.

                   Martin B"aker
                   e-mail <baeker@x4u2.desy.de>